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ALBERT i; 'rHUNaLL .AND JoHNM. HEDSTROM, 0F BUFFALQ, NEW YORK.`

Letters Patent No. 77.780, datedMay 12, 1868.

IMPROVEMENT IN ROTARY STEAM-ENGINES.

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TO ALL WHOM IT MAY CONOERN:

Be it known that we, ALBERT I. THUNELL and JOHN M. HnDsTRoM, of Buffalo, in the county of Erie, and State of New York, have invented a certain new and useful Improvement in Rotary Engines; and we do hereby declare that-the following is a full and exact description thereof, reference being'had to the accompanying drawings, making part of this specification, in which- Figure 1 is au elevation of the cylinder, showing the 'apparatus for operating the valve.

Figure 2, a similar view, with the outer plate removed.

Figure 3 is a perspective view ofthe pis-ton and its adjuncts.

Figure 4 is a vertical cross-section of the engine.

Like letters of referen'ceindicate corresponding parts in all the figures.

Our invention relates to the construction and arrangement ofthe piston-head, and the means vfor operating the valve, as hereinafter described.

In the drawings, A indicates the cylinder or case, B the piston-head, and C the valve.

- The piston-l'iead'is cylindrical, and it has a radial wing, D, extending out so as to strike against the inner periphery of the case. To produce a more perfect steam-tight packing, We provide the wing with a packingslide, D', having a rightsangled edge, a, shutting over the outer edge of the wing, so as to furnish a broad bearing at that point, and held in place by screws b b, passing through slots c c, as the wing is pressed up by a spring, d. This arrangement compensates for wear, and always keeps the joint tight, by reason of the broad bearing a, which can wear but slowly.

The induction-steam pipe E opens through the end of the cylinder directly against the end of the pistonhcad, while thc eduction-ppe G opens from the periphery ofthe cylinder on thc other side of the valve.

The end of thc piston-head next the induction-pipe has a groove,f, extending concentrically around, in line with the pipe, but having a blank, n, of such extent as to correspond with the passage of the piston-Wing from one side to the other past the valve. From this groove a passage, g, extends longitudinally through the pistonhcad, and at the opposite end opens into gnothergroovmf', fig.V 2, similar tof, except that it has no blank, n. Both grooves open just in the rear of the piston-wing by notches-hh, and thus allow it motion by the steam that enters from th induction-pipe.

The: steam forces thcpiston-wing 'around till' it comes to lthe exhaust, Gr, and in passingstill further it is necessary that the valve C should rise, 'as indicated in red lines,tig. 2, te allow it passage.

To accomplish this, we connect outside, with the nxisp of the valve, a crank-arm, H, pressed forward by springt', and in a slot, le, of saiil crank-arm, wc connect a bar, I, jointed at the. opposite end to a rock-lever, K, pivoted at l, and its short arm resting against hub L, where it is acted upon to raise the valve by acam-pin, m.

The operation will be readily understood. The steam entering behind the wing, the latter will be forced around t-o thlc exhnust, which nearly complet-cs the revolution. At this moment the cam-pin m strikes the rocki lever K, and raises the valve, while the wing passes under, which it does by reason of the momentum gained.

A special feature of novelty in this case is the arrangement of the steam-groovesff in the ends of the piston, and the passage g connecting them. r The groovef, being concentric with 'the end of the induction-pipe, and extending a'long distance around, allows a constan-t iow ofthe steam to force the piston. At the moment, however, that the piston reaches the exhaust, the blank, n, comes opposite theinduction-pipe, and cuts off the passage till after the wing haspassed the valve, when it opens anew.

At the same time the steam passing through the vpassage g, lls the opposite groovef, and not only acts upon the wing in the same manner at the opposite end, thus equalizing the action, but it balances thepiston-` head perfectly, so that the latter'moves freely and easily. Were the steam to-strike full against one end ofthe piston', the same would be practically inoperative. i

By this arrangement ofthe steam-grooves we are enabled to dispense'with a multiplication of pistonswings or paddles, and u se only one instead, whergby the friction is` greatly lessened, and the parts are less liable to derangement, the full pressure of-the steam. all the way roundbeing at the same time sec'ured, and the cutting off and letting on ofthe steam are accomplished without anfaccurate packing ofthe valve, which is necessaryin other arrangements.

We prefer to have the ends of the valve rest upon shoulders or ledges of the casejust in line with the periphery of the piston, to prevent undue friction upon said piston.

What we claim as our invention, and desire to secure by Letters Patent, is The arrangement of the concentric steam-grooves ff', passage or passages g, and blank, n, when. combined with the piston-head B, and steam-pipes E G, n the manner and for the purposevspecifiecl.

We also claim, in` combination with the wing D, the spring-slide D', with right-angled packing-edge a, arranged and operating as herein set forth.

We also claim, irl-combination with the valve C, the crank-arm H, connectng-bnr I,`1'oclcleve1 K, and eampin m, the whole arranged and operating :ts-herein set forth. l

p In witness whereofrwe have hereunto signed our names in the presence of two subscribing witnesses.

l ALBERT I. THUNELL, JOHN M. 4HEDSTROM.

Witnesses:

J. R. DRAKE, ALBERT HAIGHT. 

